1. Field of the Invention
This invention relates to optical scanners and more particularly to optical scanners using sensors for determining scanner position.
2. Description of the Prior Art
It is known in the art to use optical scanning devices in a variety of applications. For example, U.S. Pat. No. 4,088,981 issued to Stephen Gott discusses a hand-held optical scanner used in conjunction with an optica character recognition unit (OCRU) which scans characters across a page as a means for entering data into a computer. U.S. Pat. No. 4,240,748 issued to Blanc, et al. discusses another type of hand-held optical scanner used with an OCRU. These scanners typically include an array of photosensors which detect dark and light portions of a page and therefore the presence of printed characters. The photosensors are electrically coupled to an OCRU which identifies the printed characters and enters the characters into a device such as a computer memory.
In the prior art, determining the position of an optical scanner with respect to a page is a problem which has been dealt with in a number of ways. For example, U.S. Pat. No. 3,238,501 issued to Mak, et al., suggests a mechanism whereby an optical scanner is constrained to motion along a particular path. In this way, it is necessary to track scanner position with respect to only One dimension. Other optical scanning devices require complicated software algorithms to determine the position of the scanner on the page.